1. Field of the Invention
This invention relates to drive systems for transmitting rotational power to an output and more particularly, to a sectional drive system which is characterized by multiple, splined, interlocking drive segments that each include truncated and tapered exterior splines extending from one surface of a round segment base and interior splines extending from the opposite surface of the segment base and having interior spline seats located between the interior splines, which interior spline seats are substantially complementary to the configuration of the exterior splines. The drive segments are nested and interlocked by inserting the exterior splines of one drive segment in the congruent interior spline seats between adjacent interior splines of the adjacent drive segment, and are rotated in concert as a drive string in a selected path. The path may be straight or curved and in the latter case, the interlocking drive segments are capable of slight angular shifting on each other while maintaining a drive configuration of high integrity to dampen the drive vibration, define the chosen curved drive path and facilitate transmission of rotation from a drive mechanism to an output device with considerable torque and thrust. The nested drive segments can be interconnected interiorly by means of a cable or rod or exteriorly by floating collars and therefore, can be used as a drive train in any application in which a transfer of rotation is required in a straight line or at substantially any angle or deviation from a straight line. The sectional drive system may, for example, be used to effect horizontal drilling or coring of producing hydrocarbon intervals in oil and gas wells, utilizing the multiple, stacked and tapered, interlocking drive segments driven by a downhole drilling motor at one end of the drive string to operate a drill bit connected to the opposite end of the drive string. Retrieval of the drive string from the interval may be typically facilitated by a cable extended through openings in the drive segments. Consequently, the sectional drive system of this invention can be used in a downhole drilling apparatus to more efficiently effect drilling deviation in a controlled manner from a vertical well bore and provide a primary horizontal deviation or a lateral deviation from an existing vertical well bore. In a preferred embodiment of the invention, a drill bit having a removable center bit insert is mounted on the bottom one of the drive segments on the drive string, and is characterized by multiple interior splines which engage the companion exterior splines of the drive segment.
While capable of being operated in an extremely efficient manner to permit horizontal or angular drilling of drain hole perforations in oil wells, the sectional drive system of this invention can also be implemented to transmit rotational power from substantially any drive system to an output apparatus, drive or other system under circumstances where the rotational power is to be transmitted in an offset or a curved line. Accordingly, the sectional drive system of this invention is preferably designed with truncated drive segments and is capable of being used to transmit rotation from an engine, motor or other power source to automobiles, mud motors and like apparatus and equipment, as well as to dental drills, robotic devices and material-handling equipment, in non-exclusive particular.
2. Description of the Prior Art
Conventional techniques for effecting the transmission of rotational power between a power source and an output under circumstances where the power is to be transmitted in an offset or curved manner, includes the use of coupling mechanisms such as a universal or xe2x80x9cCVxe2x80x9d joint which are well known to those skilled in the art. For example, many devices have been designed for lowering into an oil or gas well for the purpose of boring and drilling holes at right angles to the well bore at the production interval, but many problems have been encountered using these systems. Typically, the relatively low bit rotational speed generally necessitated by using curved shafts of various design sometimes requires excessive time to achieve significant penetration, and increasing the bit rotational speed and torque load frequently causes failure of the shafts. Accordingly, these conventional horizontal drilling devices have not proved capable of sustaining the high compressive loads necessary to penetrate the well casing, concrete sheath, rock and producing interval in a well within an economical time frame without failure. Other problems have been encountered, such as impediments to bit retrieval and reduced freedom of rotation of the drilling string in such application.
Among the directional drilling apparatus designed to achieve this function are those detailed in the following U.S. Patentes: U.S. Pat. No. 1,367,042, to Granville; U.S. Pat. No. 2,516,421, to Robertson; U.S. Pat. No. 2,539,047, to Arutunoff; U.S. Pat. No. 2,726,847, to McCune; U.S. Pat. No. 2,778,603, to McCune; U.S. Pat. No. 3,667,556, to Henderson; U.S. Pat. No. 3,903,974, to Cullen; U.S. Pat. No. 3,958,649, to Bull et al; U.S. Pat. No. 4,051,908, to Driver; U.S. Pat. No. 4,185,705, to Bullard; U.S. Pat. No. 4,368,986, to Cousins; U.S. Pat. No. 4,442,908, to Stenbock; U.S. Pat. No. 4,601,353 to Schuh et al; U.S. Pat. No. 4,625,815, to Spies; U.S. Pat. No. 4,658,916, to Bond; U.S. Pat. No. 4,699,224, to Burton; U.S. Pat. No. 4,880,067, to Felsma; U.S. Pat. No. 5,337,839, to Warren et al; U.S. Pat. No. 5,373,906, to Braddick; U.S. Pat. No. 5,392,858, to Peters et al; U.S. Pat. No. 5,413,184, to Landers; U.S. Pat. No. 5,699,866, to James E. Cousins et al; U.S. Pat. No. 5,911,283 to James E. Cousins.
It is an object of this invention to provide a sectional drive system for transmitting rotational power in a straight path or a deviated, curved or offset path to an output of selected character.
Another object of this invention is to provide a sectional drive system for transmitting rotational power in a straight path or in a curved path offset from a source of power to an output, which sectional drive system includes multiple, splined, interlocking drive segments that are stacked and nested to rotate as a drive string responsive to application of rotational power to one end of the drive string in order to rotate the output at the opposite end of the drive string.
A still further object of this invention is to provide a sectional drive system of selected length and size, the drive system including multiple, splined, interlocking drive segments which each includes a round segment base having multiple protruding, tapered and truncated exterior splines, as well as alternating interior splines and interior spline seats in the base for receiving the projecting, tapered and truncated exterior splines of an adjacent drive segment. Multiple exterior base splines provided at the bases of the exterior splines on one drive segment engage multiple interior base splines provided on the adjacent drive segment. The drive segments are stacked and nested as a drive string within or without a guide path such as a tube, with the segments typically interconnected by a cable, rod or floating xe2x80x9ccollarxe2x80x9d for dampening drive mechanism vibration and transmitting rotational power between the drive system and an output.
Yet another object of this invention is to provide a sectional drive system having drive segments with asymmetrical splines and coupled to a drill bit for drilling one or more drain holes of selected depth and angle into a producing interval of an oil or gas well to increase the flow of hydrocarbons or gas from the interval into the well bore.
A still further object of this invention is to provide a self-contained sectional drive system characterized by multiple, splined and interlocking drive segments which can be stacked and nested, optionally on a cable, shaft or rod as a drive string, or fitted with locking grooves and cooperating external floating collars, in a straight or curved guide path. One end of the drive string is connected to a drive apparatus such as a mud motor and the opposite end to an output such as a drill bit. The drive string is typically rotated by the mud motor to drill a hole through the well casing, cement sheath and damaged formation and undamaged production formation and increase the flow of hydrocarbons into the well bore of an oil or gas well.
Still another object of the invention is to provide a transverse down-hole drilling system which is self-contained and includes multiple, cable-mounted, splined and interlocking drive segments. The drive segments each have a round base and multiple, asymmetrical, tapered and truncated exterior splines each having a drive face and spline support face of unequal area projecting from one surface of the base, and companion interior spline seats which alternate with interior splines that extend from the opposite surface of the base. The drive segments nest and rotate in concert as a drive string, and adjacent drive segments are capable of pivoting or positioning at an angle on each other in a curved guide path to define a corresponding configuration of the drive string while maintaining an interlocking configuration of high integrity. The curved guide path may be shaped in such a manner as to permit sufficient lateral movement to traverse a path bend at any predetermined angle with an output such as a drill bit attached to the lower end of the string and an input such as a downhole electric or hydraulic drilling motor coupled to the upper end of the drive string for effecting rotation of the drive string and drill bit. The drive segments may be interconnected by means of an internal cable, a rod or shaft or multiple internally-flange floating collars, to define the drive string.
These and other objects of the invention are provided in a new and improved sectional drive system for transmitting rotational power from a drive source or apparatus of selected character to an output device of selected design, such as a drill bit, in a straight guide path or in a curved guide path in any angle from 0 to 90xc2x0 under circumstances where the drive apparatus and the output device are misaligned. The sectional drive system is characterized by multiple, splined and interlocking drive segments which typically include eight spaced-apart asymmetrical, tapered and truncated exterior splines extending from one surface of a round base and each having a drive face and an angular spline support face of unequal area. Typically eight asymmetrical interior splines extend from the opposite surface of the base and define interior spline seats between the interior splines for receiving the congruent or complementary exterior splines of an adjacent drive segment in driving relationship. Multiple exterior base splines are provided at the bases of the respective exterior splines, and the exterior base splines of one drive segment mesh with respective interior base splines provided at the extending ends of the respective interior splines of an adjacent drive segment. The drive segments may be optionally slidably mounted on a cable or rod or externally connected by internally flange floating collars mounted in corresponding locking grooves of the drive segments and stacked and nested as a rotatable drive string, one end of which drive string is attached to a drive mechanism and the opposite end to an output device. In a preferred embodiment of the invention, the output device is a drill bit having a removable center bit insert, and is characterized by multiple interior splines which engage the companion exterior splines of the terminal drive segment of the drive string.